It is fairly common practice for farmers having larger farms to plant more than one crop. In the Midwest, a farmer may plant both corn and soy beans and in western states, a farmer may plant corn and wheat. Typically, corn being the larger crop, is planted in a row spacing of about 30″, using presently available hybrid corn. Soybeans may be planted at smaller spacings such as 15″ spacing, depending on the preferences and equipment of the farmer.
Since the planting season typically may include only a relatively few days of good planting weather, it has become highly desirable to minimize the amount of time necessary to convert a planter from one crop to another. One solution to the above-mentioned problem is to provide a tandem planter, that is, two identical planters, one pulled behind the other with the row units of the two planters being offset so that the row units of the rear planter are located to form furrows midway between the furrows formed on the forward planter. However, tandem planters are expensive and have a considerable length such that they become unwieldily in making critical field maneuvers and in transport.
Another attempt to provide interplant row units is to mount the interplant units on the same mounting bar as the regular units so that the mounting units are side by side across the planter frame. This is possible and enables the achievement of 15″ rows because commercial row units of a desirable type having double disc furrow openers and adjacent gauge wheels are available and they have a nominal width of about 15″, leaving 15″ between adjacent row units modeled to plant row spaced at 30″. There are, however, difficulties with such arrangements. It has been found in practice that when row units are mounted on a common bar in side-by-side relation, the adjacent gauge wheels of adjacent units are very close to one another and provide a natural trap for unbroken clods of soil or trash such as corn stalks or remaining unburied crop. This problem has become exacerbated with modern conservation planting techniques which leave more and more trash on the surface of the soil. Moreover, side-by-side positioning of row units unduly restricts access for farmers to replenish seed or other material in the hoppers or bins for the row units or to repair same, when required.
Some attempts at solving the above-identified problem have been to mount some individual row units in front of one or more transverse bars so that these units are pushed or driven rather than pulled. While this arrangement permits easy access to the hoppers for replenishing the commodity in the hopper, it also requires pushing at least half of the units which is less satisfactory than pulling all of the units. Moreover, using both push and pull row units may require separate hydraulic mechanism for lifting and lowering the units and for placing the support wheels or drive wheels of the agricultural implement so as not to interfere with the operation of the row units.